Gluten free: Mineral free? LIBS reveals all

Ezine

Mineral deficit

Laser-induced breakdown spectroscopy (LIBS) has been used for the rapid analysis of concentrations of ash, potassium, and magnesium in gluten free flour.

There are good medical reasons to opt for a gluten-free diet if you have coeliac disease. In this condition with a strong genetic link ingestion of gluten is associated with long-term autoimmune problems primarily of the small intestine. It leads to chronic diarrhoea, abdominal distention, malabsorption of nutrients, low appetite, and in children failure to grow normally. There have been claims in recent years that otherwise healthy people might benefit from reducing their intake of gluten, which is nominally a group of water-insoluble proteins found in wheat and some other grains such as barley, and rye. However, evidence for any benefits is scant in the absence of disease and recent revelations concerning gluten intolerance research cast doubt on their being a health issue associated with gluten beyond those with coeliac disease.

Nevertheless, many people opt for a gluten-free diet for various reasons and as such may suffer the ill-effects of mineral deficiencies given the apparent low mineral content of products made with gluten-free flour.

Flour mixtures

Maria Markiewicz-Keszyckaa, Maria Casado-Gavalda, Xavier Cama-Moncunill, Raquel Cama-Moncunill, Yash Dixit, Patrick Cullen, and Carl Sullivan of the School of Food Science and Environmental Health, Dublin Institute of Technology, in Dublin, Ireland, have investigated this issue in detail. Writing in the journal Food Chemistry, they explain that the rising incidence of coeliac disease, non-coeliac wheat sensitivity and health food trends, means an increased use of gluten-free foods and a need to improve nutritional content of such breads, pastas, breakfast cereals and baked goods. They explain that gluten-free flour mixtures can have raw materials rich in minerals and mineral premixes added in order to fortify them.

Nevertheless, the team suggests that effective monitoring of the elemental composition of gluten-free products is important in order to ensure those eating such products are indeed getting a balanced micronutrient diet. Numerous techniques are available but many are complicated and long-winded. The team has thus turned to LIBS in order to develop a simple but effective analytical tool for measuring mineral content of gluten-free products.

Bake off, back off

LIBS is a form of optical emission spectroscopy. It can be carried out quickly and without chemical additives. Moreover, it allows multiple elements to be analysed simultaneously. In its simplest manifestation, a laser pulse is applied to a sample, which leads to surface ablation, the spectrometer is then used to record the characteristics of the resulting plasma plume.

The team has used LIBS and combined it with chemometrics to look at the mineral content of gluten-free flours of tapioca, potato, maize, buckwheat, brown rice and a gluten-free flour mixture. The team's Principal Component Analysis (PCA) analysis of the data showed that they could discriminate between the different types of gluten-free flour. For quantification, the researchers developed a partial least squares regression (PLSR) model.

"The study revealed that LIBS combined with chemometrics is a convenient method to quantify concentrations of ash, potassium and magnesium and present the potential to classify different types of flours," the team concludes.

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